U.S. patent number 4,678,480 [Application Number 06/790,325] was granted by the patent office on 1987-07-07 for process for producing and using syngas and recovering methane enricher gas therefrom.
This patent grant is currently assigned to M.A.N. Maschinenfabrik Augsburg-Nurnberg AG. Invention is credited to Peter Heinrich, Klaus Knop, Friedbert Rube.
United States Patent |
4,678,480 |
Heinrich , et al. |
July 7, 1987 |
Process for producing and using syngas and recovering methane
enricher gas therefrom
Abstract
A process for producing a synthesis gas containing methane and
using a reactor having a fuel containing carbon comprises directing
gasification gases in a circulation system through a bed of fuel
containing carbon to form a synthesis gas containing methane and
carbon dioxide. Thereafter, the synthesis gas is cooled in a
regenerator and subjected to the gas separation wherein the syngas
is subjected to a gas cleansing by means of a pressure change
absorption in a gas scrubber to remove most of the methane and
carbon dioxide and its water content is increased. The separated
gas is then heated and subsequently the portion is returned into
the system together with the waste gases and fuel containing
carbon. The process includes a 4-pole heater which includes the
first heat exchange passage for the syngas which is cooled and a
second heat exchange passage for the recirculation of the syngas
and is further cooled and passed through a scrubber. The system
includes a heater which is arranged after the 4-pole heater which
operates the gas and then the gas is passed through a reduction
reactor back through a heating element of the regenerator that
initially cooled the gas. A portion of the gas is also used to
drive a steam turbine and to direct the excess steam from the
turbine into the initial reactor which has a fluidized bed of the
carbon material such as coal.
Inventors: |
Heinrich; Peter (Oberhausen,
DE), Knop; Klaus (Geldern, DE), Rube;
Friedbert (Munich, DE) |
Assignee: |
M.A.N. Maschinenfabrik
Augsburg-Nurnberg AG (DE)
|
Family
ID: |
6248977 |
Appl.
No.: |
06/790,325 |
Filed: |
October 23, 1985 |
Foreign Application Priority Data
|
|
|
|
|
Oct 27, 1984 [DE] |
|
|
3439487 |
|
Current U.S.
Class: |
48/197R;
48/DIG.1; 48/206; 75/707; 252/373 |
Current CPC
Class: |
C10J
3/463 (20130101); C10K 1/04 (20130101); C10K
1/02 (20130101); C10J 3/54 (20130101); C10J
2300/0959 (20130101); C10J 2300/0976 (20130101); C10J
2300/1884 (20130101); Y10S 48/01 (20130101); C10J
2300/1675 (20130101); C10J 2300/093 (20130101) |
Current International
Class: |
C10J
3/46 (20060101); C10J 3/54 (20060101); C10J
003/46 (); C10J 003/59 (); C22B 005/12 () |
Field of
Search: |
;252/373
;48/197R,203,202,206,DIG.1 ;75/35,91 ;55/26,68 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Kratz; Peter
Attorney, Agent or Firm: McGlew and Tuttle
Claims
What is claimed is:
1. A method of producing and using a high quantity of high grade
syngas with very little power consumption, and using a gasification
reactor a fuel containing carbon materials and producing a methane
plus carbon dioxide containing syngas as a product and also using a
4-pole heat exchanger having two inputs and two outputs, a
condenser, a regenerator having a cooling element and a heating
element, and a PSA scrubber, comprising: passing the syngas from
the gasification reactor to the cooling element of the regenerator
for cooling the syngas; passirg the cooled syngas into one of the
inputs of the 4-pole heat exchanger and out through one of the
outputs of the 4-pole heat exchanger for further cooling the cooled
syngas; passing the further cooled syngas through the condenser for
removing condensate from the further cooled syngas to produce a dry
syngas; subjecting the dry syngas to scrubbing in the scrubber two
remove separate portions of gas, one portion being high in methane
and the other portion being high in carbon dioxide, and a hydrogen
rich syngas leaving the scrubber; passing the hydrogen rich syngas
through the other input of the 4-pole heat exchanger and out
through the other output of the 4-pole heat exchanger for heating
the hydrogen rich syngas to produce a heated hydrogen rich syngas
subjecting the heated hydrogen rich syngas to a partial oxidation
in an ore reduction reaction to produce a waste gas, passing the
waste gas through a heating element of the regenerator for heating
the waste gas, and supplying the heated waste gas to the
gasification reactor to react with the fuel containing carbon
material, and wherein the heated hydrogen rich syngas is supplied
to a steam generating heater to be further heated thereby before
the heated hydrogen rich syngas is supplied to the ore reduction
reactor and supplying some of the one portion of gas which is high
in methane, as fuel, to the steam generating heater for generating
steam.
2. A method according to claim 1 including supplying some of the
steam generated by the steam generating heater to the gasification
reactor for reacting with the waste gas and with the fuel
containing carbon material.
Description
FIELD AND BACKGROUD OF THE INVENTION
The present invention relates particularly to a process for the
production of synthesis gas (syngas) where the gas produced in a
reactor through the gasification of fuel containing carbon is
cooled in a regenerator and subjected to treatment, and where part
of the gas is recycled to the reactor together with fuel gas and
fuel containing carbon, with the gas being heated in the
regenerator before re-entering the reactor.
A process of this kind for the production of syngas is known from
Applicant's German patent No. 3223702. This process is
characterized by a low energy consumption, since the high
temperature energy of the gas leaving the syngas reactor is used
for the heating of the recyle gas before it re-enters the
reactor.
Under the gasification conditions prevailing in the reactor this
process produces a crude gas with a comparatively low hydrogen
content and with virtually no methane at all. To improve the
hydrogen content of the gas, it must be passed through a high
temperature converter.
SUMMARY OF THE INVENTION
The present invention is based on the task of specifying a process
for the production of syngas with a relatively high methane content
which has a particularly low energy requirement and therefore can
be implemented with high economy. Furthermore, the conversion stage
is omitted in this process which is to provide syngas particularly
well suited for the direct reduction of ore.
In the process according to the present invention, further cooling
of the syngas in a 4-pole heat exchanger and a condenser during gas
treatment is carried out while also treating the syngas in a gas
scrubber for removing most of the methane and carbon dioxide,
before it is admitted to a heater after having been re-heated by
passing again through the 4-pole heat exchanger, and at least part
of the additional process steam produced in the heater is admitted
to the gasification reactor.
In the process according to the present invention the crude gas,
having passed through the regenerator, is cooled in the 4-pole heat
exchanger and the condenser to below its dew point. The thermal
energy withdrawn from the gas is not discharged, but is re-fed into
the cycle at those points where it is required. This process is a
simple way of producing high hydrogen syngas for the direct
reduction of ore, while also obtaining methane as a most valuable
by-product which can be used as syngas in chemical processes, such
as for the production of methanol, or as fuel gas in other
processes.
According to another alternative of the present process, the syngas
is routed in such a way that after its first passage through the
4-pole heat exchanger it passes through the heater.
The process further provides for oxygen to be introduced as fuel
into the gasification reactor, to improve the gasification reaction
of the coal charged into the reactor, together with the process
steam which is to increase the reactivity of the coal. It is of
advantage for the energy balance of the process if part of the
process steam excess energy is employed for the production of
oxygen to be used in the reactor.
A typical example of the process covered by the present invention
will now be detailed by reference to a flow sheet. The illustrated
drawing is a block diagram of the plant for the production of
syngas to be charged into an ore reduction reactor.
Accordingly it is an object of the invention to provide an improved
method for producing synthesis gas containing methane which uses a
reactor having a fuel containing carbon and which includes
directing gasification gases in a circulating system through the
bed of fuel containing carbon to form a synthesis gas containing
methane and carbon dioxide and then cooling the syngas and
subjecting the syngas to a gas separation with a portion of the gas
which is separated being returned into the system together with the
waste gases and the fuel containing carbon and a portion subjected
to a gas cleansing by means of a pressure change absorption and a
scrubber to remove most of the methane and carbon dioxide and the
water content of the gas is increased.
A further object of the invention is to provide a system for
processing syngas which includes a fluidized bed reactor containing
coal into which gasification gases which include oxygen, steam and
recirculated gases are directed and thereafter the syngases which
are formed are directed through cooling elements to cool the gases
through a scrubber for removing the methane and carbon dioxide with
a portion being compressed and sent to a further heater in a
reduction reactor and for eventual return into the system and
another portion being used to generate steam in a system which uses
a regenerator having separated hot and cold elements permitting an
initial passage of the gas through the cooling elements and a
subsequent passage through a heating element.
A further object of the invention is to provide an apparatus which
is simple in design, rugged in construction and economical to
manufacture.
The various features of novelty which characterize the invention
are pointed out with particularity in the claims annexed to and
forming a part of this disclosure. For a better understanding of
the invention, its operating advantages and specific objects
attained by its uses, reference is made to the accompanying drawing
and descriptive matter in which a preferred embodiments of the
invention is illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
The only figure of the drawings, FIG. 1, is a schematic
representation of a synthesis gas producing apparatus for the
process of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawing in particular the invention embodied
therein comprises a system for the process of producing a synthesis
gas containing methane which uses a reactor 1 having a fuel
containing carbon therein. The drawing also shows at various
locations of the system in numerals which are enclosed in
rectangular enclosures at locations of the portions of the system
which are found in corresponding notations in the tables set forth
in the present invention.
In accordance with the invention, gasification gases including
oxygen, steam and waste gases are directed into the reactor 1
through a fluidized bed of a common material such as coal to
produce synthesis gases which contain methane and carbon dioxide.
The synthesis gases which are formed are then cooled in a cooling
element of a regenerator 3 and thereafter subjected to a gas
separation which occurs as the gases are passed through a 4-pole
heat exchanger 4, a condenser 5 and a scrubber 6 and a return
circulatin in which the gases again pass through another section of
the 4-pole heater 4. A portion of the gases are directed through a
heater 8 and a reduction reactor 9 and returned as gasification
gases into the fluidized bed reactor 1. A 4-pole heat exchanger as
shown at 4 in FIG.1, has two input pipes at 4.2 and 6.1 and two
output pipes at 4.3 and 6.2 , for a total of 4-pipes or poles.
According to the flow sheet, carbon in the form of fine-grain,
reactive pulverized coal is charged into a fluidized bed reactor 1.
High temperature process steam oxygen, and recycle gas are fed into
the reactor 1 as gasification agents. The analysis of the recycle
gas is given in Table No. 1, column 3.0
In the ractor 1 the coal is gasified at a temperature of
800.degree. C. and a pressure of 10 bar. The ash during the
gasification process is discharged at the reactor bottom. The
synthesis crude gas leaves the reactor at the top with an analysis
according to column 4.0 fo Table No 1.
Having passed through a flue ash or dust separator 2, the crude gas
enters the cooling element of a regenerator 3 for being cooled from
800.degree. C. to 578.degree. C. Suitable regenerators which in a
cooling element withdraw heat from a hot gas flow, while also
storing the heat and transferring it via a heating element to
another gas flow are known to the expert, amongst others, from
blast furnace processes and the glass making industry, and are not,
therefore , described in greater detail. Further cooling of the gas
is provided in a 4-pole heat exchanger 4 and a condenser 5,
reducing the gas temperature to 60.degree. C. Any condensate
obtained in the condenser 5 is drained.
Downstream the condenser 5 the gas is subjected to PSA scrubbing at
6 for the selective separation of the methane and carbon dioxide
proportions of the syngas from the gas flow. The scrubbing process
follows a well known absorption method according to which specific
gases to be separated from a gas flow are absorbed by a solid
matter, for being subsequently removed by means of a purging gas,
such as nitrogen, after a flashing process. The separated methane
and the carbon dioxide are sluiced out of the process for different
uses.
The gas scrubber considerably increases the hydrogen content of the
syngas, such as is shown in column 6.0 of Table No. 1. The syngas
has now the very analysis required for subsequent ore
reduction.
Downstream the gas scrubber 6, the syngas is fed into a compressor
7, after which it once again passes through the 4-pole heat
exchanger 4 for being heated to 466.degree. C. Before being
admitted to the reduction reactor 9, the gas flow first passes
through a heater 8 for the additional production of process steam
required for the process and where through combustion of part of
the methane separated in the gas scrubber 6 the syngas is heated to
such a high lever that, having passed through the heater 8, it
enters the ore reduction reactor 8 at a temperature of 900.degree.
C.
In the reduction reactor 9, where iron ore is directly reduced into
sponge iron, the syngas is partly oxidized during the reduction
process, upon which it leaves the reactor 9 with a lower hydrogen
content, as shown in column 3.0 of Table no. 1. This gas, referred
to as top gas, is admitted to the heating element of the
regenerator 3 for being heated to 750.degree. C. and the readmitted
to then gasification reactor 1 as a high temperature recycle
gas.
The high temperature water steam produced in the heater 8 is used
for driving a steam turbine 10, with the turbine power output
virtually covering all the electrical energy requirements of the
process. Part of the turbine power is used in an air separation
process at 11 for the production of oxygen such as is required for
coal gasification. The oxygen is then compressed and fed into the
gasification reactor 1.
The exhaust steam from the steam turbine 10 is admitted to the
reactor 1 as process steam, having previously been heated to
750.degree. C. in the regenerator 3. Heating the process steam in
the regenerator 3 in addition to the top gas, means a further means
improvement of the process energy balance. Of course, the top gas
and process steam flows need not be routed in separate piping but
can be combined before the inlet of the regenerator 3 for common
heating.
TABLE NO. 1 ______________________________________ Process Unit
Coal Oxydant Top Gas ______________________________________
Variable 1.0 2.0 2.1 3.0 3.1 Volume Flow Nm.sup.3 /s -- 1.815 1.815
34.05 37.93 Mass Flow Gas kg/s -- 2.585 2.585 20.71 20.38 Solid
kg/s 6.23 -- -- -- Temperature .degree.C. 20 20 450 402 750
Pressure bar 10 1 10 10 10 Gas Analysis H.sub.2 /C0 -- -- -- 5.45
5.87 H.sub.2 +CO vol. % -- -- -- 53.84 53.73 H.sub.2 vol. % -- --
-- 45.49 45.91 CO -- -- -- 8.35 7.82 CO.sub.2 -- -- -- 7.30 6.90
H.sub.2 O -- -- -- 31.32 31.32 CH.sub.4 -- -- -- 4.93 5.22 H.sub.2
S -- -- -- 0.00 N.sub.2 -- 2.0 2.0 2.61 2.83 O.sub.2 -- 98.0 98.0
-- ______________________________________ Process Unit Crude Gas
Dry Gas ______________________________________ Variable 4.0 4.1 4.2
4.3 5.0 Volume Flow Nm.sup.3 /s 50.25 43.81 Mass Flow Gas kg/s
24.33 29.84 solid kg/s 0.32 0.0 Temperature .degree.C. 800 800 578
358 60 Pressure bar 10 9.5 9.2 8.9 8.5 Gas Analysis H.sub.2 /CO
6.23 6.23 H.sub.2 +CO vol % 59.21 67.92 H.sub.2 vol % 51.03 58.52
CO 8.19 9.39 CO.sub.2 17.49 20.06
______________________________________ Process Unit Crude Gas Dry
Gas ______________________________________ Variable Gas Analysis
H.sub.2 O 14.99 2.49 CH.sub. 4 6.25 7.17 H.sub.2 S 0.09 0.10
N.sub.2 1.97 2.26 O.sub.2 -- --
______________________________________ Fuel Process Unit Reducing
Gas Gas ______________________________________ Variable 6.0 6.1 6.2
6.3 7.0 Volume Flow Nm.sup.3 /s 34.30 1.746 Mass Flow Gas kg/s
13.58 1.356 solid kg/s Temperature .degree.C. 60 86 466 900 60
Pressure bar 80 100 10 10 10 Gas Analysis H.sub.2 /Co 6.23 --
H.sub.2 +CO vol. % 86.75 -- H.sub.2 vol. % 74.75 -- CO 12.00 --
CO.sub.2 3.18 -- H.sub.2 O 3.18 -- CH.sub.4 4.64 88.66 H.sub.2 S
0.00 -- N.sub.2 2.31 11.34 O.sub.2 --
______________________________________ Re- Con- Gas Sponge sidual
den- Scrub- Process Unit iron coke Dust sate ber
______________________________________ Variable 8.0 9.0 10.0 11.0
12.0 Volume Flow Nm.sup.3 /s 7.76 Mass flow gas kg/s 15.20 solid
kg/s 20.62 0.339 0.324 5.20 8.0 9.0 10.0 11.0 12.0 Temperature
.degree.C. 900 800 60 60 60 Pressure bar 1.0 Gas Analysis H.sub.2
/CO -- H.sub.2 +CO vol. % -- H.sub.2 vol. % -- CO -- CO.sub.2 89.14
H.sub.2 O 0.26 CH.sub.4 0.59 H.sub.2 S -- N.sub.2 -- O.sub.2 --
______________________________________ Process Excess gas Process
Unit steam (separated CH.sub.4)
______________________________________ Variable 13.0 13.1 14.0 14.1
Volume flow Nm.sup.3 /s 6.53 1.764 0.0 Mass flow gas kg/s 5.24
1.356 0.0 solid kg/s -- Temperature .degree.C. 350 750 60 13.0 13.1
14.0 14.1 Pressure bar 10 1.0 Gas Analysis H.sub.2 /CO -- --
H.sub.2 +Co vol. % -- -- H.sub.2 vol. % -- -- CO -- -- CO.sub.2 --
-- H.sub.2 O 100 -- CH.sub.4 -- 88.66 H.sub.2 S -- 0 N.sub.2 --
11.34 O.sub.2 -- -- ______________________________________ Given
Process Data Coal Analysis wt. % C 79.7 H.sub.2 5.1 O.sub.2 7.7
N.sub.2 1.5 S 1.1 Ash 4.9 Water 0.0 Net calorific value, H.sub. u
waf MJ/kg 33.06 H.sub.u real MJ/kg 31.44 Energy O.sub.2 production
kWh/Nm.sup.3 0.42 Non-combustible 4.2 Gasification temperature
.degree.C. 800 Gasification pressure bar 10 Top gas temperature
.degree.C. 750 Gas scrubber temperature .degree.C. 60 Gas scrubber
pressure bar 8 Process steam for gas kg/Nm.sup.3 -- scrubber
Electrical energy for gas kWh/Nm.sup.3 -- scrubber Reduction
temperature .degree.C. 900 Reduction pressure bar 10 Degree of
reduction, 0.945 sponge iron Fe content in the ore 0.67 Energy
conversion in the gasifier MW.sub.+n Coal 201.8 Top gas 322.3
Oxydant 1.1 Process steam 19.8 Total input 545.0 Crude gas 515.5
Losses 29.5 Total discharge/output 545.0 Correction for process 5.0
steam Electrical energy consumption MW.sub.e Air
separation,PO.sub.2 2.74 O.sub.2 compressor, PKO 0.96 Gas
compressor, PKG 1.50 Gas scrubber, PW -- Miscellaneous 0.30 Total
consumption 5.50 Covered internally 5.50 Covered externally --
Primary energy consumption/ 206.8 MW requirement
______________________________________
* * * * *